The invention relates to heating ventilation and air conditioning (HVAC) systems. More particularly, the invention relates to axial flow rotating shroud fans for such systems.
Fans are ubiquitous in HVAC systems. Many fan configurations exist. One group of fan configurations is axial flow rotating shroud or banded fans. These fans include a circumferential shroud at outboard ends of the blades. The blades and shroud of many such fans are unitarily molded of plastic to provide lightness and ease of manufacturing. Such fans are often situated closely downstream of a heat exchanger to draw an air flow across the exchanger (e.g. an air-cooled condenser).
A variety of efficiency concerns attend the design of fans and the associated environment (e.g., housings or casings). One area of efficiency loss results from the recirculation of air near the blade tips. The presence of the shroud may somewhat address this recirculation. Nevertheless, many additional mechanisms have been proposed to further reduce recirculation. For example, U.S. Pat. No. 5,489,186 shows one such proposal.